Both steady and pulsatile flow through simulated, rigid and flexible vascular stenoses will be studied in order to compare the pertinent flow characteristics to the geometry of the stenoses. As a starting point, steady state velocity profiles will be measured by photographing small particles flowing in glycerine-water solutions in rigid plexiglas tubes containing stenoses of known geometry. Pressures at the walls will be monitored, and the nature and extent of the separated regions of flow in the diverging sections of the stenoses will be measured. The results will be compared with a theoretical solution in order to assess the merits of the experimental techniques. Whole blood will then be used, and the pressures and separated regions determined and compared to those of the transparent fluid. Regions of relatively high and low pressures and wall shearing stresses will be located. Flexible models will be constructed to some of the same geometries as the rigid tubes. The effects of flow conditions on post-stenotic dilatation will be noted and, if possible, some measurements of the separation region will be made. Finally, preliminary studies on flow through mamalian arterial and/or venous segments will be undertaken and the results related to the previous studies mentioned.